When loading or unloading a vehicle (e.g., a truck, trailer, etc.) parked at a loading dock, a hook-style vehicle restraint may be employed to restrain the vehicle and prevent or restrict the vehicle from accidentally moving too far away from the dock during loading and/or unloading operations. To restrain the vehicle, a hook-style vehicle restraint engages what is often referred to in the industry as a vehicle's ICC bar (Interstate Commerce Commission bar) or RIG (Rear Impact Guard). An ICC bar or RIG includes a bar or beam that extends horizontally across the rear of a vehicle, below the bed of the truck or trailer. Its primary purpose is to help prevent an automobile from under-riding the vehicle in a rear-end collision. A RIG, however, also provides a structure for a hook-style restraint to extend around in order to obstruct the bar's and thereby the vehicle's movement away from the dock during loading and unloading operations.
To release the vehicle and allow it to drive away from the dock, the restraint is moved to a position in which it does not obstruct the movement of the bar. Sometimes, however, forward pressure from the vehicle causes the restraint's hook to catch on the bar in a way that prevents the hook from disengaging the ICC bar. Such a condition is remedied by what's known as a “bump-back,” where the vehicle backs up slightly toward the dock to release the pressure on the restraint and thus allow the hook to disengage from the ICC bar. Once the hook is no longer obstructing the vehicle's movement, the vehicle is free to drive away from the dock.